The present invention relates to machines for making rod-shaped smokers' products with dense ends, and more particularly to improvements in apparatus which are used in such machines to convert a stream consisting of tobacco particles or like fibrous material into a filler wherein portions containing larger quantities of fibrous material alternate with portions containing smaller quantities of such material. For the sake of convenience, the invention will be described with reference to the making of plain cigarettes having dense ends and consisting of natural tobacco; however, it will be understood that similar apparatus can be resorted to in the manufacture of filter tipped cigarettes as well as in the manufacture of plain or filter tipped cigarillos or cigars consisting of natural or reconstituted tobacco and/or tobacco substitutes.
There are two presently known methods of making cigarettes with dense ends. Both methods and the corresponding apparatus have found widespread acceptance in the industry for more than two decades. In accordance with the first method, a rotary cam or an analogous mechanical compacting device condenses spaced-apart (selected) portions of a continuous tobacco stream which is moved lengthwise into the range of a suitable trimming device which removes the surplus. The mechanically compacted portions of the thus obtained filler contain more tobacco than the remaining portions of the filler The means for conveying the stream past the mechanical compacting device preferably comprises a suction-operated conveyor, and the compacting device is arranged to condense the selected portions of the stream in a direction toward the suction-operated conveyor. The extent of mechanical compacting of selected portions of the stream can be such that the trimming device is incapable of removing any tobacco from the mechanically compacted portions of the stream. The filler is thereupon draped into a web of cigarette paper of other suitable wrapping material to form therewith a continuous cigarette rod which is severed to yield a succession of plain cigarettes having dense ends. The severing (by a conventional cutoff or the like) can take place adjacent to or across the densified portions, depending upon whether the cigarettes should have one or two dense ends.
An apparatus of the just outlined character is disclosed in U.S. Pat. No. 3,318,314 granted May 9, 1967 to Carl Stelzer.
In accordance with the second method, the means for removing the surplus from selected portions of a continuous tobacco stream comprises a trimming device which is designed to alternately remove larger and smaller quantities of tobacco from one side of a moving stream. This is accomplished by resorting to one or more discs having marginal portions provided with pockets for additional tobacco. The discs rotate at a peripheral speed matching the forward speed of the stream and cooperate with a surplus removing or separating device, e.g., a brush or a paddle wheel which sweeps away all particles of tobacco extending beyond the marginal portion or portions of the disc or discs. The resulting filler has portions of greater height or thickness alternating with portions of lesser height or thickness; it is converted into a rod which is wrapped in cigarette paper, and the resulting continuous cigarette rod is severed across or adjacent to portions which contain more tobacco to yield a file of plain cigarettes with one or two dense ends.
An apparatus which can be used for the practice of the just outlined second method is disclosed in U.S. Pat. No. 3,032,041 granted May 1, 1962 to Raymond Lanore.
Under certain circumstances, neither of the above outlined prior methods and apparatus is likely to produce dense-end cigarettes with a requisite degree of accuracy and reliability. This holds true especially when the cigarettes are to be manufactured at a rate of approximately or even in excess of one hundred per second, a requisite which is met by certain presently known cigarette makers such as a machine now marketed by the assignee of the present application.